Acid resistant molded articles and process of making them



ACID RESISTANT MOLDED ARTICLES AND PROCESS OF MAKING THEM Loren J. Miller, Akron, Ohio, assignor to American Hard Rubber Company, New York, N. Y., a corporation of New York No Drawing. Application June 16, 1951, Serial No. 232,047

12 Claims. (Cl. 260-28.5)

The present invention relates to acid-resistant molded articles and process of making them. More particularly, the present invention relates to a composition which is especially useful in the making of molded battery containers, such as the one-piece containers used for storage batteries and which provide a plurality of cells, in each of which electrolytic action may take place. The invention also relates to a method of making such containers. Such battery cells are commonly filled with an electrolyte, comprising an aqueous solution of sulphuric acid.

The prior art has disclosed the use of various bituminous compositions for making battery containers or cases of this general type, these containers being in general substantially less expensive than the conventional hard rubber containers which are used for similar purposes. A composition useful for this general purpose was disclosed in the patent to Woodley, No. 1,156, 122, issued October 12, 1915. This subject matter was further developed as shown by the patent to Lukens, No. 1,752,917, issued April 1, 1930, which referred to the Woodley disclosure. The present invention has as an object to improve upon compositions of this general type and which include acid-attackable fibers by increasing the resistance of such fibers to acid attack so as substantially to reduce or delay acid penetrated into a wall formed of the compositions in accordance with the present invention. Tests have shown, for example, that the penetration of acid into a wall of prior art materials in a period of twenty-eight days at 150 F. was about & inch per ASTM D639-49T test method. Inasmuch as partition walls between adjacent cells may be of the order of magnitude of inch in thickness, the penetration of inch from each direction toward the center left an unattacked partition only inch in thickness in the center. This relatively thin portion of the partition was easily cracked due to its weakened condition, with the result that a short circuit was formed between the adjacent electrolyte baths, effectively terminating the useful life of the battery. While it is recognized that the temperature in question (used for test purposes) is somewhat higher than that customarily met with in ordinary use, at least in these climates, the time period at which the penetration test was made was also much shorter than the intended useful life of a battery. The test was and still is, therefore, considered characteristic of the effectiveness of the compositions as battery container material.

Natural or artificial fibers of organic material, particularly cellulosic fibers, for example paper scraps or cotton linters, are a desirable and relatively cheap ingredient, providing a desired mechanical strength to the composi' tion in use. It is, therefore, a general object of the present invention to protect this strengthening material so as substantially to reduce, if not wholly to eliminate, the penetration of acid into a wall formed of such a composition, and hence greatly to increase the useful life of a battery having a container made of the composition forming the subject matter of the present invention.

The prior art has more recently disclosed a composinited States Patent ice.

tion which is satisfactory for certain purposes for making compositions of the character to which the present invention pertains and for making battery cases therefrom, this prior art consisting of the patent to Dillehay, No. 2,501,995, issued March 28, 1950. While certain of the prior art teachings have provided methods by which fibrous material of a cellulosic character such as cotton is protected fairly well, fibrous materials such as that sold under the trade-name Nylon is not adequately protected against acid. Inasmuch as one source of fibrous material for compositions for use in making battery cases is often fibrous material reclaimed from old tires, and as such tires are now often built with Nylon cords or fibers, there is a present need for protecting this type of material, which need is met by the present. invention.

The present invention, therefore, may be summarized as an improvement in a composition, using the basic ingredients of the prior art aforesaid, i. e., asphalt; a fibrous material, at least a substantial part of which is of an acidattackable nature; and an acid resistant mineral filler, all in substantially the proportions which have become standard in this art over a period of years. These basic materials are now used in conjunction with a new protective material, which is supplied and admixed with the other materials in the proportions of about 1% to about 6.9%, but preferably up to about 2 /2% of the weight of the entire composition, and wherein the essential active ingredient of the protective material is either resorcinol or phloroglucinol, the resorcinol or phloroglucinol being present to the extent of at least about 0.5% by weight of the entire composition and either constituting all the protective material or being admixed with an extender material, namely, monomeric furfuryi alcohol. No poly- V merization catalyst, either acidic or basic, is required or is present in compositions in accordance with the present invention.

The present invention was made as a result of an extended research program, looking to find some satisfactory protective materials which could be used with the basic ingredient materials of the prior art (asphalt, mineral filler and fiber as aforesaid) for the purpose of protecting the articles made therefrom from acid attack, and particularly for the purpose of protecting the fiber ingredient of the composition from acid attack. This research also had as an object to provide a composition wherein some Nylon fiber could be used and be reasonably protected from acid attack, it having been found by experiment that this type fiber is much more difiicult to protect than is cotton or similar cellulosic fibers.

In the course of this research, it was found that resorcinol and phloroglucinol are each effective alone to produce the desired results, while other monoand dihydroxybenzenes are not effective to any corresponding extent. For example, as will be set forth in detail hereinafter, phenol cannot be substituted for resorcinol with equivalent results, neither can hydroquinone or catechol, even though the latter two compounds are the para and ortho substituted dihydroxy-benzenes respectively, while resorcinol is the meta dihydroxy-benzene. Phloroglucinol seems to be at least as effective as resorcinol, and is to be considered within the purview of the present invention, even though it is so expensive as compared with resorcinol as to be commercially prohibitive at this time. These and other comparisons will be demonstrated by actual examples of tests made as hereinafter set forth.

A further discovery forming a part of the present invention is based upon certain tests set forth hereinafter in greater detail showing that while monomeric furfuryl alcohol, when used alone and without resorcinol, is ineffective to obtain any desired results in accordance with the present invention, the combination of such monomeric e furfuryl alcohol with resorcinol in the proportions hereinafter set forth, will be effective to obtain results corresponding in desirability (acid resistance of the final product) for most purposes to the results obtained and obtainable by the use of resorcinol alone. The present invention, therefore, is intended to cover the use of resorcinol alone or in conjunction with monomeric furfuryl alcohol. Such combined use is desirable as monomeric furfuryl alcohol is relatively cheaper than is resorcinol and, therefore, result in desired compositions which can be produced at a minimum cost, and a corresponding minimum cost for the final products, for example, battery cases.

Considering now the details of compositions in accordance with the present invention, such compositions consist substantially of the following ingredients: (a) asphalt, acting as a binder, (b) a pulverulent acid resistant mineral filler, (c) a strengthening fiber, a substantial portion at least of which is of an acid-attackable organic nature, and (d) a protective material for protecting the composition as a whole, and particularly the acid-attachable fiber ingredient thereof, from attack by acid with which the final article formed from the composition may be brought into contact.

These several ingredients will now be discussed in detail as to their characteristics and amounts to be used.

(a) The binder material or asphalt in this case may be of various compositions, such as various manufactured asphalts, pitches, or mixtures thereof, the particular composition not being critical as far as is now known. It is contemplated that the asphalt ingredient functions mechanically to tie or bind the other materials together into a substantially homogeneous composition in use. Asphaltic compositions in accordance with the Woodley, Lukens or Dillehay patents above referred to are satisfactory for use as this ingredient of the composition. These materials may be natural asphalts or those remaining from oil refining operations after the removal of the more volatile portions, or may be derived from coal tar. They may also include pitches of various kinds.

It has been found that the material set forth in detail in the patent to Spelshouse ct al., No. 2,455,709, issued December 7, 1948, and assigned to Socony-Vacunm Oil Company, Incorporated, is a satisfactory material. The material coming within the specific definition given in this patent as set forth in the claims thereof, and which was purchased from the assignce of record of that patent, was in fact used as the asphalt ingredient in all the tests hereinafter given as examples in the present application. It has also been found that the specifications set forth for the asphalt in claim 1 of this Spelshouse et al. patent can be varied to provide a slightly harder type asphalt, which has now been adopted for commercial use by the owners of the present application. These differences involve the change of the ball and ring softening point of the asphalt from the range given in the Spelshouse et al. patent (claim 1) to the range of 290 F. to 305 F.

In accordance with the present specifications for asphalt, there is also introduced a factor of ductility at 160 F. of 3 cm. to 6 cm. per ASTM test Dll3-44 with jaw separation of 0.4 inch per minute. This characteristic was not set forth, in the claims at least, of the Spelshouse et al. patent. In general, as set forth in the Dillehay patent aforesaid, the characteristics of the asphalt are not critical, but rather will affect the corresponding characteristics of the final product. The present invention is directed primarily to the acid resistance of the final product, which appears to be a separate and distinct characteristic from any provided by variation in the asphalt ingredient.

The asphalt ingredient of the composition of the present invention should be from about 40% to about 55% by Weight of the entire composition. These limits are not narrowly critical, but are a general guide to the approximate amount of this ingredient usable for most commercial purposes, such as the making of battery cases.

(b) The acidresistant filler contemplated for use in accordance with the present invention is substantially chemically inert in character and may be of any material which is relatively proof against attack by battery acid. Among the materials which are presently considered suitable for this purpose are powdered coal, powdered glass, pyrophyllite, the pulverulent material resulting from the grinding or polishing of glass, and possibly other materials of a generally similar nature. As far as is now known, this material functions in a mechanical way only and does not enter into the composition by any chemical reaction. As further requirements as to this material, it is desirable that this material have a small particle size, such that substantially all of it will pass through a IOU-mesh screen.

This material will be present in an amount principally determined by difference between the total of the other materials herein set forth and In general, there will be about 35% to 45% filler in most compositions usable commercially in accordance with the present invention for the making of such articles as battery cases. Again, these limits are not narrowly critical, but depend upon the amount of other materials used and the characteristics desired in the final product, other than the characteristic of acid resistance to which the present invention particularly pertains. In general, as the amount of filler is increased, the amount of asphalt must be more or less similarly increased in order to provide a cohesive final product.

(0) The fiber used in the composition in accordance with the present invention is provided in order mechanically to strengthen the composition, by mechanically tying together the other materials previously described. While it is, of course, possible to use some non-acidattackable fiber such, for example, as glass fiber in compositions of this general character, such non-acidattackable fibers as can be used are generally more expensive than are the acid-attachable fibers, which latter are usually of an organic nature. Thus, it is contemplated that the fiber which will be used, at least to a substantial extent, will be material selected from a wide variety of cellulosic fibers and also other suitable fibers of wholly synthetic origin, such as Nylon, the selection usually being dictated by economic factors, rather than by the chemical characteristics of the material. For example, scrap kraft paper may be used, as may also be cotton linters. Second cut cotton linters, Government grade 5 to 6, is a preferred material in this respect. It has been found that the fiber derived from used tires is eminently satisfactory for use as part, if not all, of the fiber requirements of the present composition. Inasmuch as some of these fibers may be Nylon, it is a purpose of the present invention to provide a composition wherein this Nylon is protected as far as reasonably possible from attack by acid. The fiber length is not particularly important, although it is contemplated that the longer length fibers will be generally somewhat superior to shorter length fibers.

The amount of fiber to be used in the composition may be varied within certain limits. In general, if a greater amount of fiber is used, correspondingly larger amounts of the protective material will be required. The increased amount of protective material which may be needed to afford necessary protection in turn will tend to make the entire composition somewhat softer and more easily subject to bulging due to heat and pressure. Thus the practical upper limit of both combined is that composition which will be undesirably subject to heat-softening as measured by a bulge test at some predetermined temperature. This tendency to bulge may be offset to some extent by using a relatively harder asphalt as a binder.

While quite wide varieties of percentage composition as to fiber may be used, as taught, for example, in the prior art, wherein 5% to 17% by weight of the entire composition was contemplated, it is usually preferred in the=makingof battery cases to operate within-somewhat narrower limits, specifically within about 11% to about 13%. Furthermore, while the total amount of fiber for the desired composition should be in this range, it is contemplated that a part only of this fiber may be of an acid-attachable nature. When there is some substantial proportion of fiber in the entire composition which is of an acid-attackable nature, the necessity for the use of the protective material of the present invention arises. This necessity becomes greater if the fiber is of an especially vulnerable type such as Nylon.

(d) The protective material, which is used to reduce, if not wholly to prevent, acid penetration into the composition when it is brought into contact with an acid as is a storage battery case, is an essential ingredient of the composition of the present invention. It has been found that this protective material may be present in the final composition to the extent of about 1% up to about 6.9%, but preferably only up to 2 /2%, by weight of the entire composition. These limits are not narrowly critical and are arrived at as follows. If less than about 1% of the protective material be used as hereinafter demonstrated as a result of actual tests, the acid penetration progressively increases beyond what are now considered to be acceptable limits. This change in degree of acid penetration, while progressive in nature, crosses practical commercial limiting values, which are established more or less arbitrarily by users of the articles made of the compositions according to the present invention. When the penetration of acid is greater than some arbitrary value set by such a user, the article is no longer commercially saleable to that user and hence must be sold at a lower price, if at all. For this reason, therefore, 1% of the protective material by weight based on the entire composition weight has been chosen as providing a minimum protection which will be satisfactory to many, if not all, commercial users of battery cases, and may be considered as a limit established in commercial practice for the scope of the protection desired for the present invention.

The preferred upper limit of 2 /2% herein stated is again not critical. Larger amounts of protective material may be used, if desired. Here, however, the limitation is imposed not by the characteristics of the material to a great extent, but rather by economics, it being uneconomical to use more than this amount, for this amount will give adequate and satisfactory results. Substantially more than this amount of the protective material and up to about 6.9% may be used without introducing any undesired characteristics in the final article. Examples will be given illustrating the results obtainable by the use of amounts of the protective material up to 6.9%. The limitation of 2 /2% is, therefore, chosen as a preferred upper limit consistent with the economics of the process and the final product, the protective material being more expensive than the average of the remaining materials in the composition. A limiting value, therefore, for the upper limit is about 6.9%, which is the highest amount of the protective material which is illustrated by examples herewith; and as even this amount is probably above the desired economic limit; while about 2.5% is the preferred upper limit dictated by economics. It has been found that when substantially greater amounts of resorcinol are added (than 6.9%), undesired results from the point of view of the characteristics of the final product are obtained.

The one essential ingredient of the protective material in accordance with the present invention is a chemical material or compound which is basically a substituted benzene ring type compound in which there are at least two OH groups substituted at position meta to one another. Such materials include, but are not limited to, resorcinol and phloroglucinol. Of these two materials, resorcinol is usually preferred, solely by reason of the realtive cost of the two materials, which is greatly in favor of resorcinol as of the present time. For this reason, therefore, most of the research Work which has been done and which is set forth in examples hereinafter given, is restricted to resorcinol. This material may, if desired, be used alone and will give desired results as hereinafter illustrated by actual examples including numerous tests. However, resorcinol may be used in conjunction with monomeric furfuryl alcohol. From one point of view, therefore, furfuryl alcohol may be considered as an extender or substitute in part for some of the resorcinol This extender material cannot be used alone to give satisfactory results, as has been demonstrated as a result of tests. When resorcinol is combined with monomeric furfuryl alcohol, there should be at least 0.5% to about 1.5% resorcinol present, while the furfuryl alcohol should be present in an amount up to about 2%. Normally, the furfuryl alcohol will be present in the range of about 0.5% to about 2%. In all cases in accordance with the preferred concentrations given above, the total of resorcinol plus furfuryl alcohol (if used) will be as stated above from about 1% to about 2 /2 of the total composition. These percentages are all given as weight percentages of the total composition. Again, if higher percentages than 2 /2% are used, minimum amounts remain the same and the higher percentages are permissible as resorcinol, or resorcinol plus furfuryl alcohol, up to about 6.9%. The use of resorcinol plus furfuryl alcohol seems to be effective in all proportions within the ranges given. These principles will be demonstrated in detail by results of actual tests hereinafter given.

When furfuryl alcohol is used, the resulting composition is softened to some extent, which should be compensated for in the choice of the character and amount of the other materials, as will be obvious to those skilled in the art.

It has further been found that the use of protective materials in accordance with the present invention serves to impart desired protection against acid penetration, even when some or all the fiber used is Nylon. This appears also to be true in respect to other synthetic fibers which may be difficult to protect in respect to the difiiculty of protecting cotton or other cellulosic fibers, although all such other synthetic fibers have not been tested as they are not normally used in compositions of this kind.

The theory of the operation of protecting the composition and particularly the acid-attackable fiber ingredient thereof, by following the teachings of the present invention, is not clearly or definitely understood. There will be stated for what it may be worth, some of the theories presently considered as explaining in part at least the desirable results which are actually obtained.

Considering the protection of cotton (cellulosic fibers), it is believed that the fibers in the final product, when formed into an article such as a battery case, are generally oriented due to the plastic flow of the material during the molding process; and that a high percentage of the individual fiber ends start at the surface of the article and extend toward the center of a wall thereof, such as a partition wall between the cells of a battery case. It is believed reasonable to assume that the tar residuum (asphalt) covering the outside ends of the fibers is quite thin, or non-existent, due to the wiping action of the molding surface. Thus, a single fiber with one end. at the partition or wall surface and the other nearer to the partition or wall center, is covered by a thin film of tar residuum (asphalt) containing particles of the inert mineral filler, such as pyrophyllite and coal dust. When then sulphuric acid (such as battery acid) contacts the fiber, 9. reaction is believed to occur between a hydroxyl group of the cellulose and the sulphuric acid, resulting in sugar formation due to splitting off of water molecules. Sap rises in trees due to the osmotic pressure exerted by a sugar solution on the semipermeable cellulose membranes, so that analogous result from the degradation of the cellulosic fiber in the asphalt composition by battery acid is believed to permit the sugar solution plus acid to penetrate further droxy-aryl compounds.

into the fiber and other adjacent fibers. The addition of a component compatible with the hydrophilic material as well as with hydrophobic, hydrocarbons (asphalt) is believed to induce better association of the cellulosic fibers and the petroleum tar residuum (asphalt) and/ or to retard the action of the battery acid due to this resultant compatibility.

It is further believed that the peculiarly effective action of resorcinol in this case is due to the presence therein of a double activated hydrogen atom connected to carbon at the 2-position in the ring, between the carbons (at 1 and 3 positions) to which the --OH groups are bonded. It is considered that a nuclear hydrogen, ortho to a hydroxy group in the ring is thereby activated. Thus, of the several 'hydroxy-substituted benzenes, only in resorcinol and phloroglucinol are there double activated hydrogen atoms, bonded to carbon in this way. It is believed that this double activation in some way permits the resorcinol to protect the cellulosic fibers from attack by acid in a Way and to an extent that cannot be done by inactivated or singly activated hydrogen in a more or less similar compound.

It is recognized that this explanation is not complete and further that it does not take into account the matter of partial replacement of some of the resorcinol by monomeric furfuryl alcohol. It is, however, the best explanation that can be given at this time. In any event, no particular theory of operation is relied upon in support of the appended claims, as this case merely points out the manner in which desirable and reproducible results can and will always be obtained, and the composition and variants thereof within the limits of the present invention.

In combining the ingredients aforesaid in accordance with-the present invention, any desired or usual method and/or apparatus for combining materials of this kind may be used. Theorder in which the materials are mixed together is not critical or vital to the success of the composition or to the method of making it. It has been found in practice that good results may be obtained by introducing all the ingredient materials aforesaid into a suitable inixer in any order and at temperatures at which these materials may be satisfactorily mixed, usually between about 300 F. and about 400 F. and preferably about 350 PX, at which temperature the asphalt ingredient is reasonably low in viscosity. A thorough mixing should be effected so as to produce a substantially homogeneous mixture. This mixing is explained in some detail in the Woodley patent aforesaid, and is not per se a part of the present invention.

It may, in some instances, be desired first to mix the fiber ingredient with the protective material and then as a second step to blend the mixed fibers and protective material with the other ingredients. This, however, is not essential as aforesaid.

The molding of the material may be effected in any conventional manner, for example, in the manner in which battery cases or other articles have been formed for many years in accordance With the teachings of the Woodley patent, the Lukens patent, and with the commercial art generally. Again, neither the details of the molding process nor the apparatus used therewith are per se parts of the present invention.

The novel character of the present invention and the limits of usefulness thereof are amply demonstrated by 6 the following examples, in each of which there will be given an outline of the point or principle being demonstrated:

' EXAMPLE I 7 This example s given to illustrate the relative protective-effect of resorcinol as compared with other hy- In each instance in the table which follows, the same mixture of asphalt, filler and fiber, was used, and inall instances this mixture of asphalt, I

filler andfiber, was made up in theweight ratio of 600 grams of asphalt of the type set forth in the Spelshouse et al, patent aforesaid, 570 grams of an acid resistant mineral filler as aforesaid, and 180 grams of cotton (cellulosic) fiber} The percentages hereinafter given represent the total weight percentage of the protective material in the entire composition. The acid penetration measured in 64ths of an inch was determined by tests as set forth hereinabove, wherein a test piece made up in a conventional manner was tested in acid for a period of 28 days at 150 F. per ASTM, #D639-49T test method. This test method has now become standard in this industry as characteristic of acid penetration and is acceptedby makers and users of battery cases as satisfactory.

Table 1 Percent Acid pene- Te st N0. Protective Material Protective tration Material 8-10 3.5 7-8 3.5 8-8 6.9 8-8 6.9 8-8 6. 9 -6 6.9 0-3 6.9 7-8 6.9 7-9 6.9 complete 6.9 5-7 6.9 1-3 5.25 3-4 3.6 3-4 2.5 4-5 1. 45 5-6 6.9 4-5 6.9 5-6 s phloroglucinol 2.5 0

For most commercial purposes, penetrations of not over 3 and sometimes less are required. From the above it is concluded that the only satisfactory materials for use in relatively small amounts are resorcinol and phloroglucinol and hydroquinone in relatively larger amounts. Inasmuch as oneset of comparative prices taken some time ago but at the same time show a relative cost of 74 cents per pound for resorcinol, $10 per pound for phlorglucinol, and 98 cents per pound for hydroquinone, it is concluded that phloroglucinol is not now commercially competitive for achieving the purposes of the present invention; and further thatthe relatively large amounts of hydroquinone required as compared to resorcinol make hydroquinone commercially unattractive.

EXAMPLE II This example is forthe purpose of showing the effect of different amounts of resorcinol combined with the same composition for the remaining materials. in each case this composition was compounded in the proportions of 600 grams asphalt of the type set forth in the Spelshouse et a1. patent aforesaid, 570 grams inert mineral filler as aforesaid, and 180 grams cotton fiber. To this basic material was added different amounts of resorcinol, test pieces made from these different mixtures and acid penetrations tested as above set forth thereon, with the results given in Table II which follows.

Table II Resoreinol Acid Pene- -Test; N0. tration Grams Percent From the above it is concluded that in order to keep the acid penetration within permissible limits, there should be at least about 1% resorci I101 present in the composition; and further that percentages of resorcinol, greater than 2 /2, do not serve to give any better results from the point of view of prevention of acid penetration, than those available by the use of this preferred upper limit of resorcinol. Under these circumstances and as resorcinol is more expensive than are the other ingredients of the composition, a practical economical upper limit of about 2 /2 is chosen for the purpose of this case.

EXAMPLE III The purpose of this example is to illustrate the effect upon the characteristics of the final composition of a variation in the filler content thereof. In each instance the protective material used was resorcinol and in each instance the batches were calculated so that the percentage of resorcinol used was about 1.83, which value is central of the desired range as hereinabove set forth. The eifect of variation in filler is demonstrated by the tests set forth in Table III as follows:

Table III Test No a b c d e Asphalt (Grams) a 600 600 600 600 600 400 Filler (Grams) r. 200 400 600 800 1, 000 Fiber (Cotton) (Grams) 180 180 180 180 180 100 Protective Material (Resorcinol) (Grams) 14. 5 18 22 26 29. 5 28 Acid Penetration (in let. of an inch) 1-2 1-2 1-2 1-2 1-2 0 From the above it is concluded that while the percent filler affects certain physical properties, particularly tensile strength and percent elongation, it does not in any Way affect the degree of protection afforded for the composition and particularly for the fiber ingredient thereof by the protective material.

EXAMPLE IV This example is presented to illustrate the effect on the several properties of the composition of varying percent of fiber therein. In all cases the other factors are held constant as far as possible, the amount of protective material being calculated so that it will represent about 1.83% by weight of the total composition, as in Example 111. It is noted that acid penetration is not affected.

This example illustrates the effect of using a mixture of resorcinol with monomeric furfuryl alcohol, or from another point of View, of substituting some monomeric furfuryl alcohol for some of the resorcinol.

In each test for this example, the same basic batch of materials was used, namely, 600 grams asphalt of the same character as in the previous eaxmples, 570 grams filler of the same character as aforesaid, and 180 grams of cotton fiber of the same character as aforesaid. To each of these basic compositions was added a total of 35 grams (about 2.5% of the total weight) of a protective material, the only difference between these several tests given in this example being in the composition of the protective material as set forth in Table V which follows. In each case the batch was mixed for 5 minutes in a steam-heated laboratory banbury mixer at 350 F. The mixed mass was then placed in a mold, pressed and cooled by the Water-cooled platens of the press.

Table V Composition of Modi lying Material Acid Pene- Test No. tration (in Monomeric $64 of an Resorcinol Furfuryl inch) (grams) alcohol From the above it is concluded that there should be at least about 0.5% by weight resorcinol in the protective material; that monomeric furfuryl alcohol alone is not satisfactory, but that any amount of resorcinol including at least 0.5% by weight of the composition, plus monomeric furfuryl alcohol, will be satisfactory to give desirable results when the total amount of protective material present in the composition is within the general preferred limits given above.

EXAMPLE VI In a series of tests under this example, the same basic mixture of asphalt, filler and fiber was used with a total of 2 /2 of a protective material consisting of 25% resorcinol and monomeric furfuryl alcohol, only the character of the filler being changed. With five different types of commercially available fillers which were tried, the acid penertration in each case was kept within de sired limits not greater than 1-2 in any case. From these tests it was concluded that the chemical character of the filler material does not affect acid peneration when using a desired combination of resorcinol and monomeric furfuryl alcohol in accordance with the present invention.

EXAMPLE VII The tests in this example show the effect of added varying amounts of the protective material to the basic composition, which, as aforesaid, consists of 600 grams of asphalt of the character previously set forth, 570 grams of filler, 180 grams of cotton fiber, and wherein the pro tective material in each case set forth in the tests in Table VII following, consisted of 25% resorcinol and 75% of monomeric furfuryl alcohol, both by weight. The only variation between these tests was in the total amount of the protective material added in each test as set forth.

Table VII Protective Material Test No. Acid Penetration Grams Percent 11 0 0 8-10 b- 10 t). 73 3-6 15 1. 10 3-4 d 20 1. 46 23 25 1. 82 2-2 30 2. 18 1-2 35 2. 5 0-2 50 6 0 ii. 9 0

75 Nylon instead of all cotton as in all the prior examples given. With; a total weight of fiber of 180 grams combinedwith600 grams of asphalt and 570 grams of filler, several tests were made using the same type of polymerized furfuryl alcohol resin taught by the prior art. Under these circumstances, as the portion of the weight of Nylon in respect to the total fiber (180 grams with the balance cotton in each case) increased from grams to l80, the acid penetration went from about 2 to about 8-9. In each instance there was 2 /2% of the protective material used.

Resorcinol was then substituted as a protective material forv the polymerized furfuryl, alcohol resin of the prior art which was tested as aforesaid. Using the same proportions of all the ingredients with the exception of the protective material, and using in each test 25' grams of resorcinol (about 1.8% by weight) and similarly varying theamount of Nylon to cotton, the acid penetration goes from about l-3 with 175 grams of cotton and 5 grams of Nylon to 2-3 with 180 grams of Nylon and no cotton. It is concluded, therefore, that resorcinol alone is effective substantially to reduce the acid penetration when the fiber contains a substantial amount, or consists wholly, of Nylon.

A similar series of tests were run using as a protective material a mixture of 25% resorcinol in 75cc. monomeric furfuryl alcohol, in each case a total of 1.83% by weight of the mixture (protective material) being used as compared with the weight of the total composition. Again the Nylon content of the fiber was varied from 0.36% of the total weight of the composition to 13%, the balance of the fiber in each instance being cotton, and the total weight of fiber being the same (13%) in each instance. Under these circumstances, the acid penetration varied from 2-2 up to 4-5 and was only 2-3 when the total Nylon content of the fiber was not over about half of the fiber present (when tested in the same way set forth in Example I hereof).

A similar series of tests were tried using all Nylon fiber (13% by weight of the composition) in the same asphalt-filler combination, and varying the proportions of resorcinol to furfuryl alcohol from the proportion of 4 grams of resorcinol and 96 cc. furfuryl alcohol to 40 grams resorcinol and 60 cc. furfuryl alcohol. None of the tests in which there was less than 30 grams resorcinol present showed satisfactory resistance against acid penetration, but the results showed decided improvement with increasing proportions of resorcinol with an acid penetration of 3-4 for 40 gm. resorcinol to 60 cc. furfuryl'alcohol. Thus, when all the fiber is Nylon, it maybe concluded that the resorcinol may not be diluted more than to about equal parts with furfuryl alcohol.

A further series of tests were made-using a total of 1.83% by weight protective material in thesame basic asphalt-filler-fiber composition, wherein there was 25% resorcinol and 75% monomeric furfuryl alcohol used as the protective material. In this case, the fiber was varied from all cotton through various proportions with viscose rayon, to all rayon. circumstances, varied progressively from a maximum of about 2 with all cotton up to 3-4 with all rayon. This illustrates that viscose rayon is more diificult to protect than is cotton, but that the use of the present invention serves to minimize acid penetration.

The present invention-has been described generally inthe foregoing description; limits have. been given. of. the

use of it and bases for these limits set out. Everyessential' principle set forth has been illustrated by. the results of actual tests which have been made. Some variations of the preferred process and compositionin accordance,

with the present invention have been taught hereinabove,

and others will occur to those skilled in the art from..the.

foregoing particular description. It-is intended that all reasonable equivalents of the subject matter particularly disclosed shall be considered to be within the purviewof the present invention and within the scope of the appended The acid penetration, under these claims, which are to be construed validly as broadly as the state of the prior art permits.

What is claimed is:

1. An acid-resistant molded article formed from a composition consisting essentially of' (a) a binder of asphalt in an amount of about 40% to about 55% by weight of the composition; (b) a strengthening fiber in an amount of about 7% to about 17% by weight of the composition, including a substantial amount of an acid attackable organic fiber; (c) a protective material to protect said acid-attackable fiber from attack by acid.

with which said article may be brought into contact and in an amount of about 1% to about 6.9% by weight of the composition, said protective material consisting essentially of the following essential active ingredients: monomeric resorcinol in an amount of at least about 0.5% by weight of the entire composition and monomeric furfuryl alcohol from 0% up to the balance of said protective material in the composition, said composition as. a Whole being substantially free of any material capable. of catalyzing (1) monomeric resorcinol, (2) monomeric furfuryl alcohol or (3) a mixture of monomeric resorcinol and monomeric furfuryl alcohol, to the form of polymerized or condensed resins respectively; and (d) the balance of the composition consisting essentially of acidresistant mineral filler.

2. A molded article in accordance with claim 1, in which the asphalt used as ingredient a is one having a ring and ball softening point of about 250 F. to about 305 F., and a needle penetration at F., 50 grams,

5' seconds, of about 5 to 16 mm.

3. A molded article in accordance with claim 1, in which the protective material constituting ingredient 0 consists essentially of monomeric resorcinol in an amount of about 0.5% to about 1.5% by weight of the entire composition, and monomeric furfuryl alcohol in an amount of about 0.5% to about 2% by weight of the entire composition; and in which the fiber constituting ingredient b is present in an amount of about 11% to about 13% by weight of the entire composition.

4. A molded article in accordance with claim 1, wherein said asphalt has a ring and ball softening point of about 290 F. to about 305 F.

5. A molded article in accordance with claim 1, wherein said protective material consists essentially of resorcinol.

6. A molded article in accordance with claim 1, wherein a substantial partat least of said fiber is of a synthetic organic nature.

7. A molded article in accordance with claim 1, in which the protective material consituting ingredient 0 consists essentially of monomeric resorcinol in an amount of about 0.5% to about 1.5% by weight of the entire composition, and monomeric 'furfuryl alcohol in an amount of about 0.5 to about 2% by weight of the entire composition; and in which the fiber constituting ingredient b is of an acid-attackable-nature and is presentv in an amount of about 11% to about 13% by weight of the entire composition.

8. The process of increasing the resistance to acid attack and pentration of a molded'article formed from a composition consisting essentially of (a) a binder of asphalt in an amount of about 40% to about 55% by weight of the composition; (b) a strengthening fiber in an amount of about 7% to about 17% by weight of the composition, including a substantial amount of an acidattackable organic fiber; (c) a protective material to protect said acid-attackable fiber from attack by acid with which said article may be broughtinto contact and in an amount of about 1% to about 6.9% by weight of vthe composition, said protective material consisting essentially of the following essential active ingredients: monomeric resorcinol in an amount of at least about 0.5% by weight of the entire composition and monomeric furfuryl alcohol from 0% up to the balance of said protective material in the composition, said compositionasa whole beingsub-- stantially free of any material capable of catalyzing (1) monomeric resorcinol, (2) monomeric furfuryl alcohol or (3) a mixture of monomeric resorcinol and monomeric furfuryl alcohol, to the form of polymerized or condensed resins respectively; and (d) the balance of the composition consisting essentially of acid-resistant mineral filler; said process comprising the steps of blending the named ingredients into the composition aforesaid, and molding an article from the composition thus formed.

9. The process in accordance with claim 8, wherein said protective material consists essentially of resorcinol.

10. The process in accordance with claim 8, in which the protective material constituting ingredient c of said composition consists essentially of monomeric resorcinol in an amount of about 0.5 to about 1.5% by weight of the entire composition, and monomeric furfuryl alcohol in an amount of about 0.5 to about 2% by weight of the entire composition; and in which the fiber constituting ingredient b is present in an amount of about 11% to about 13% by weight of the entire composition.

11. An acid-resistant molded article formed from a composition consisting essentially of (a) a binder of asphalt in an amount of about 40% to about 55% by weight of the composition; (b) a strengthening fiber in an amount of about 7% to about 17% by Weight of the composition, including a substantial amount of an acidattackable organic fiber; (c) a protective material to protect said acid-attackable fiber from attack by acid with which said article may be brought into contact and in an amount of about 1% to about 6.9% by weight of the composition, said protective material consisting essentially of the following essential active ingredients: at least one chemical material consisting essentially of a benzene ring in which there are at least two OH groups substituted at positions meta to each other and said chemical material being selected from the group consisting of monomeric resorcinol and monomeric phloroglucinol, said chemical material being present in an amount of at least 0.5% by weight of the entire composition, and monomeric furfuryl alcohol from 0% up to the balance of said protective material in the composition, said composition as a whole being substantially free of any material capable of catalyzing (1) monomeric resorcinol, (2) monomeric phloroglucinol, (3) monomeric furfuryl alcohol, or (4) any mixture of at least two of the materials: monomeric resorcinol, monomeric phloroglucinol, and monomeric furfuryl alcohol, to the form of polymerized or condensed resins respectively; and (d) the balance of the composition consisting essentially of acid-resistant mineral filler.

12. An acid resistant molded article in accordance with claim 11, wherein said chemical material is phloroglucinol.

References Cited in the file of this patent UNITED STATES PATENTS 1,370,637 Erwin Mar. 8, 1921 1,409,104 Henderson et a1 Mar. 7, 1922 2,033,870 Smith Mar. 10, 1936 2,162,747 Rector June 20, 1937 2,314,181 Winterkorn Mar. 16, 194-3 2,501,995 Dillehay Mar. 28, 1950 2,541,631 Baskin Feb. 13, 1951 2,647,090 McColgan July 28, 1953 OTHER REFERENCES Gregory: Uses and Applications of Chemicals and Related Materials (1939), page 504. 

1. AN ACID-RESISTANT MOLDED ARTICLE FORMED FROM A COMPOSITION CONSISTING ESSENTIALLY OF (A) A BINDER OF ASPHALT IN AN AMOUNT OF ABOUT 40% TO ABOUT 55% BY WEIGHT OF THE COMPOSITION; (B) A STRENGTHENING FIBER IN AN AMOUNT OF ABOUT 7% TO ABOUT 17% BY WEIGHT OF THE COMPOSITION, INCLUDING A SUBSTANTIAL AMOUNT OF AN ACIDATTACKABLE ORGANIC FIBER; (C) A PROTECTIVE MATERIAL TO PROTECT SAID ACID-ATTACKABLE FIBER FROM ATTACK BY ACID WITH WHICH SAID ARTICLE MAY BE BROUGHT INTO CONTACT AND IN AN AMOUNT OF ABOUT 1% TO ABOUT 6.9% BY WEIGHT OF THE COMPOSITION, SAID PROTECTIVE MATERIAL CONSISTING ESSENTIALLY OF THE FOLLOWING ESSENTIAL ACTIVE INGREDIENTS: MONOMERIC RESORCINOL IN AN AMOUNT OF AT LEAST ABOUT 0.5% BY WEIGHT OF THE ENTIRE COMPOSITION AND MONOMERIC FURFURYL ALCOHOL FROM 0% UP TO THE BALANCE OF SAID PROTECTIVE MATERIAL IN THE COMPOSITION, SAID COMPOSITION AS A WHOLE BEING SUBSTANTIALLY FREE OF ANY MATERIAL CAPABLE OF CATALYZING (1) MONOMERIC RESORCINOL, (2) MONOMERIC FURFURYL ALCOHOL OR (3) A MIXTURE OF MONOMERIC RESORCINOL AND MONOMERIC FURFURYL ALCOHOL, TO THE FORM OF POLYMERIZED OR CONDENSED RESINS RESPECTIVELY; AND (D) THE BALANCE OF THE COMPOSITION CONSISTING ESSENTIALLY OF ACIDRESISTANT MINERAL FILLER. 